The processing of a black-and-white photographic material usually comprises the steps of developing, fixing and washing the material. The processing of a color photographic material usually comprises the steps of color developing, bleaching, fixing and washing the material. The fixing step allows the removal of silver ions in the developed photographic material by formation of a soluble complex with the fixing agent. The fixing agent generally comprises a thiosulfate, e.g., sodium thiosulfate or ammonium thiosulfate. The soluble complex of silver and thiosulfate is removed from the material by washing.
Replenishment of the wash tank in a photographic material processor, e.g., a graphics art film processor in a similar way and in similar amounts to the replenishment of the developer and fixer tank, can lead to a substantial reduction in the amount of water consumed during processing. However, simply replenishing with water means that the concentrations of silver, thiosulfate and other by-products within the wash tank build up.
Conventionally, impurities are flushed through the tank and down the drain by the volume of liquid that flows through the wash tank. In moving to a system which uses wash water in the same way as developer and fixer, the volume of solution passing through the tank may be reduced to as little as one hundredth as that passing through a standard system. Consequently, the silver concentration eventually reaches a level at which the image permanence of the photographic material may be compromised.
JP-5088305 describes a method of processing a silver halide black-and-white photographic material in which washing is effected by supplying 0.8 to 3.0 l/m.sup.2 of an aqueous hydrogen peroxide solution (0.3 to 2.0 g/l) along the direction of film transport and draining the waste water. The quantities of hydrogen peroxide employed provide sterilization and reduce the appearance of sludge or scum.
The present invention solves the problem of how to reduce the concentration of silver and thiosulfate in the wash solution, and to avoid impairment of the image.